Question: William thought it would be nice to include $\frac{4}{15}$ of a pound of chocolate in each of the holiday gift bags he made for his friends and family. How many holiday gift bags could William make with $\frac{4}{5}$ of a pound of chocolate?
Solution: To find out how many gift bags William could create, divide the total chocolate ( $\frac{4}{5}$ of a pound) by the amount he wanted to include in each gift bag ( $\frac{4}{15}$ of a pound). $ \dfrac{{\dfrac{4}{5} \text{ pound of chocolate}}} {{\dfrac{4}{15} \text{ pound per bag}}} = {\text{ number of bags}} $ Dividing by a fraction is the same as multiplying by the reciprocal. The reciprocal of ${\dfrac{4}{15} \text{ pound per bag}}$ is ${\dfrac{15}{4} \text{ bags per pound}}$ $ {\dfrac{4}{5}\text{ pound}} \times {\dfrac{15}{4} \text{ bags per pound}} = {\text{ number of bags}} $ $ \dfrac{{4} \cdot {15}} {{5} \cdot {4}} = {\text{ number of bags}} $ Reduce terms with common factors by dividing the $4$ in the numerator and the $4$ in the denominator by $4$ $ \dfrac{{\cancel{4}^{1}} \cdot {15}} {{5} \cdot {\cancel{4}^{1}}} = {\text{ number of bags}} $ Reduce terms with common factors by dividing the $15$ in the numerator and the $5$ in the denominator by $5$ $ \dfrac{{1} \cdot {\cancel{15}^{3}}} {{\cancel{5}^{1}} \cdot {1}} = {\text{ number of bags}} $ Simplify: $ \dfrac{{1} \cdot {3}} {{1} \cdot {1}} = {3} $ William could create 3 gift bags.